UV sanitisation in water treatment?

• A. It adds chlorine to water
• B. It increases turbidity
• C. It removes dissolved metals
• D. It inactivates microorganisms using ultraviolet light

Answer: (D)

UV sanitisation in water treatment relies on ultraviolet-C light to inactivate microorganisms by damaging their DNA and RNA, which prevents replication. This is a non-chemical disinfection method, so no residues are added to the water and it doesn’t remove dissolved metals or other contaminants. It works well when the water is clear enough for the UV light to penetrate; turbidity or color can hinder effectiveness. It also does not provide a residual disinfectant, so a follow-up or complementary steps may be needed if a lasting residual is required. Because of these properties, UV disinfection inactivates microorganisms using ultraviolet light.